I have an SD2 and it changes patches fine and I don't notice any delays.

I use a 5 year old Midisport Uno to connect the midi device to the computer though. The Thru cable goes to a vocal harmony box from the SD2 and this changes harmonies on the fly. I'm using Midi ch 5 for this and band in a box outputs triads on the channel you select (in my case both the box and band in a box have soloist set to midi ch 5) and you select to say send triads to the box you can see the change being sent and the chord shows up on the box.

So I know that the SD2 works perfectly with Win 7 64 bit using a Midisport USB to midi cable on the current version of band in a box because the box flashes when receiving midi and the patch changes I insert into the Soloist channel via F5 cause the box to change from say one harmony like 4 part to 2 part on the fly. This has never not worked.

I cannot speak to the SD4 being the same however, I never researched, bought, or trouble shot the SD4, and for all purposes, never had to shoot the SD2 for misbehaving.

John Conley
Musica est vita